The mandate from the special counsel's office is "limited to investigation into Russian influence into 2016 and related matters."

"Which means that everything related to everything else is for someone else to do," Zerlin added. "In the Southern District [of New York] are they interested in Russian interference or are they interested in things like campaign finance violations unrelated to Russia."

“You have Michael Cohen, who has already pleaded guilty, you have evidence of campaign finance violations, you have investigations into, now, Trump Organization business dealings, insurance fraud, tax fraud, all kinds of fraud which are unrelated to the Russia investigation,” Zelin said. “So how does the Mueller report extricate the president from his problems?”

But that doesn’t mean that people like the president, his son Donald Trump, Jr. and son-in-law Jared Kushner are not in the crosshairs of ongoing investigations at the state or federal level, the prosecutors said.

One of the big-ticket questions was what really happened at the Trump Tower meeting, and you can’t have that unless you interview Don Jr. and Jared Kushner — but Mueller didn’t do that,” said NBC News legal analyst Glenn Kirschner, a longtime federal prosecutor who worked with Mueller at the Department of Justice. “And why didn’t he do that? It wasn’t an oversight. He’s the most thorough investigator I’ve ever met. That was a tactical measure.”

Kirschner said that Mueller likely did not subpoena those individuals, who met with a Kremlin-connected attorney during the 2016 election at Trump Tower, because they remain targets of ongoing investigations.